Applicant has filed a continuing reissue application Ser. No. 09/827,380 filed on Apr. 4, 2001.
The present invention relates to a method of imaging a person or an object in at least two directions by X-ray photography, while using an X-ray cassette as a receptor or other forms of radiation-absorbing techniques with the aid of a radiation receptor, for instance for electronic image storage.
In imaging processes of this kind, there is used a radiation source which is supported for movement in X-, Y- and Z-directions and which is rotatable about a horizontal axis. The receptor unit may be mounted in or positioned beneath a patient table and is movable in the X-direction. Movement of the radiation source may be initiated automatically, as the receptor unit is moved.
By X-direction is meant here and in the following a direction of movement which is parallel with one long side of the patient table, while by Y-direction is meant a direction of movement perpendicular to the extension of said long side, i.e. a direction of movement parallel with the short sides of the table. By Z-direction is meant movement in a vertical direction. This enables the patient table to be brought to different positions in relation to a tower column or a ceiling-mounted tower which carries the beam source.
The present invention also relates to a patient table equipped with a receptor unit, and more specifically to a patient table of the kind defined in the preamble of claim 5.
GB-B-1,323,769 (Picker Corp.) describes apparatus comprising a receptor part disposed in a patient support table, and an overlying ceiling-mounted beam source. The apparatus enables side-on photographs to be taken with a horizontal beam path, by swinging-up the patient""s support table about a horizontal axis and pivoting the beam source. The apparatus also enables the image size and the shutter setting to be varied in relation to the beam-source/receptor distance (xe2x80x9cSIDxe2x80x9d, i.e. xe2x80x9csource-image-distancexe2x80x9d. However, movement of the beam source and swinging of the patient support table must be effected manually, which is experienced as troublesome by the radiologists concerned.
EP-A-0 430 934 (AO Medical Products) describes a method of the aforesaid kind in which activation of a secondary receptor pivotally associated with the receptor unit or mountable thereon and extending in a vertical plane results, optionally after a time delay, in automatic movement of the beam source to a basic setting for horizontal, centered beam path onto the secondary receptor.
A Philips brochure describes a patient support table which carries a receptor unit for a vertical beam path. This receptor unit can be swung outwards and upwards from one side of the table, to a position for receiving a horizontal beam path.
This latter arrangement, which is considered to represent the nearest prior art, has a number of drawbacks. When the receptor unit is to be swung out and up to receive a horizontal beam path, it is necessary for personnel who need to stand on the other side of the table in order to manoeuver the beam source to move around the table to swing the receptor unit outwards and upwards, and then move back around the table and place themselves in their original position in which the beam source can be manoeuvered. This procedure is experienced by the personnel as being both troublesome and time-consuming. The described solution also has other drawbacks from an ergometric aspect.
Another drawback is that the receptor unit is not centred in relation to the beam path when swung outwards and upwards from the table, and it is therefore necessary to move the beam source in the X-direction when adjusting for horizontal beam path.
Furthermore, this known arrangement only allows an exposure to be taken from one side of the patient. It is often difficult to xe2x80x9cturnxe2x80x9d the patient, particularly when the patient is seriously injured.
The effect of these drawbacks may sometimes be so serious as to impair the clarity of the pictures to an extent such as to require the X-ray to be taken again, therewith exposing the patient to an unnecessarily high radiation dosage.
One object of the invention is to provide a method and a patient support table of the aforedefined kind which, with one and the same receptor equipment, enables pictures to be taken with a vertical beam path, for instance with the patient lying down, and also with a horizontal beam path from each side of the patient support table, and preferably without changing the setting of the beam source in the X-direction, i.e. without moving the beam source laterally.
Another object is to provide equipment of the aforesaid kind which is superior to earlier known equipment with regard to ergometrics.
A further object of the invention is to provide equipment which can be adapted readily to different specific parameters, such as receptor size, table width, etc.
These and other objects are fulfilled with a method of the kind defined in the preamble of claim 1 and having the features set forth in the characterizing clause of said Claim.
The invention enables the beam to be kept central in the Y-direction in the transition between a vertical and a horizontal beam path, irrespective of the alignment of the horizontal beam path in the Y-direction. In addition, the invention enables a receptor that has been swung up to a position above the table to be moved towards the patient and therewith obtain optimum picture sharpness and therewith a clearer diagnosis from the picture or image obtained.
The invention also enables the positions of pivot centres to be determined accurately in accordance with the different parameters that apply in individual cases, for instance in accordance with the dimensions of the receptor unit, the width of the patient support table, the desire for the bottom edge of the receptor to be located at a given height above the table when the receptor is in an outwardly swung position, and so on.
The present invention also enables the introduction of mutually dependent locking facilities with a crosswise function for outward swinging of the receptor unit in the horizontal plane. The effect afforded by the invention can be likened to the hinge of a hinged door, i.e. the receptor can present alternative pivot centres in dependence on the direction in which the receptor unit is swung outwards. Left and right pivot centres can be readily adapted to occurrent types of tables.
In practice, it is preferred that respective pivot centres are so placed in the X- and Y-direction that centering of the beam source in the X-direction will be the same for both a horizontal and a vertical beam path. A preferred method according to the invention is characterized by swinging the receptor unit in one or both of the alternative outwardly and upwardly swung positions to a position in which the unit is perpendicular to the longitudinal axis of the table, therewith enabling X-ray pictures to be taken of a patient seated in a wheelchair, for instance.
This enables the requirement of a separate frame or stand for taking such pictures to be dispensed with. This special outwardly swung position of the receptor unit may also be used in other circumstances, for instance when taking lung X-rays, etc.
In one preferred method of applying the invention, the receptor unit is movable in the X-direction along the longitudinal axis of the table with corresponding automatic movement of the beam source and resetting of said source for a horizontal beam path towards the receptor unit, after having swung the receptor unit outwardly and upwardly beyond a side edge of the table.
Thus, in the case of this preferred method of application, the beam source is adjusted automatically to the position adopted by the receptor unit.
In accordance with one method of application, the receptor unit is supported by a carriage which can move in the X-direction relative to the table and which can also be moved in the Y-direction relative to the carriage. The unit is carried by arms whose lengths can be adjusted and which supports the unit stably and reliably.
In this method of application, the receptor unit can be dropped down or raised up from an outwardly swung horizontal position on each side of the table, to a respective vertical position beneath or above the table, by pivotal movement about mutually parallel axles located at different levels.
When in an outwardly swung and upwardly lifted vertical position, the receptor unit can be swung about a central, vertical axle for work with an angled beam path.
According to another aspect, the invention also relates to a patient support table provided with a receptor unit and intended for X-ray photography or X-ray exposure or some other type of beam sensing, e.g. electronic image storage, said patient support table being characterized essentially by the features set forth in the following claims 8-16.